Lehrich, who has been actively tweeting about the debate, later apologized about his tweet, but didn't delete it. He wrote, "I want to apologize for the clearly inappropriate nature and language of this personal tweet. Sorry all."

I want to apologize for the clearly inappropriate nature and language of this personal tweet. Sorry all.

He was responding to Trump's claim during the presidential debate that Humayun Khan -- whose parents spoke out against Trump at the Democratic National Convention -- would still be alive if he had been president.

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Trump said during the debate: "First of all, Captain Khan is an American hero. If I were president at that time, he would be alive today, because unlike her who voted for the war without knowing what she was doing, I would not have had our people in Iraq. Iraq was a disaster. So he would have been alive today."